1. Department of Preventive and Social Dentistry Federal University of Rio Grande do Sul Porto Alegre Brazil
2. Department of Community Oral Health, School of Medicine, Dentistry and Nursing University of Glasgow Glasgow Scotland UK
3. Faculty of Health Sciences Simon Fraser University Burnaby British Columbia Canada
4. Department of Epidemiology & Biostatistics, Graduate School of Public Health & Health Policy City University of New York New York New York USA